1. Field of the Invention
The present invention generally relates to a device for recording and/or playback of information signal to and/or from a disk-shaped recording medium, and more particularly to a pickup moving mechanism which moves an optical pickup unit.
2. Description of the Related Art
Some of the recent functionally improved portable electronics such as a notebook computer or the like have a CD-R/RWs or DVD-ROM drive installed therein. With such a functional improvement of the portable electronics, it is demanded for these CRY-R/RWs and DVD-ROM drives to be able to write or read data at an improved speed or for the DVD-ROM drive to rewrite data to a DVD.
The notebook computer of a small size (B-5 size, for example) can be carried more easily and conveniently than a larger-size one (A-4 size, for example). Therefore, the notebook computer is of smaller thickness and weight while it is functionally improved. It is also demanded that the CD-R/RWs or DVD-ROM drive used in the notebook computer should be designed as thin as possible.
An example of the conventional disk drives for recording or playing back data to or from CD-R/RWs and DVD-ROM is schematically illustrated in FIG. 1. As shown, a disk drive of this type, generally indicated with a reference number 300, includes a body 301, a disk tray 303 provided movably between two positions, outer and inner, and having a concavity in which an optical disk 302 such as DVD or the like is to be received, and an optical pickup unit 304 housed from the rear side of the disk tray 303 and which reads information signals from the optical disk 302 set on the disk tray 303.
FIG. 2 shows the body 301 of the disk drive 300, not showing the upper half of the device body 301. The device body 301 is composed of a pair of halves, upper and lower, which are butt-joined to each other. The lower half indicated with a reference number 307 is open at the front end 307a thereof for movement of the disk tray 303, and a guide member 308 provided along each of mutually opposed lateral edges 307b and 307c thereof to guide the movement of the disk tray 303. The lower half 307 has disposed at the rear end 307d thereof a printed wiring board 309 formed from a so-called rigid substrate having formed thereon various circuit patterns on which there are electronic parts such as a connector for connection to a host apparatus and the like. The printed wiring board 309 has connected thereto an FCC (flexible printed circuit) 310 for connection to the optical pickup unit 304 housed in the disk tray 303.
As shown in FIGS. 3 and 4, the optical pickup unit 304 includes an iron-made base chassis 315 as a body of thereof and having a disk table assembly 313 provided thereon, a pair of guide rails 316 installed to the base chassis 315, a pickup base 317 having provided thereon an objective lens 312 whose movement is guided by the guide shafts 316, and a pickup moving mechanism 318 which moves the pickup base 317 on and along the guide shafts 316.
A cover member 320 is fixed with a binding screw or the like at a side the optical pickup unit 304 where the optical disk 302 is to be placed. The cover member 320 has formed therein an opening 321 through which the objective lens 312 and disk table 313 included in the optical pickup unit 304 are exposed. The cover member 320 is formed from aluminum (Al), for example. It should be noted that the optical pickup unit 304 has a metallic bottom plate 322 provided on the bottom thereof. The bottom plate 322 is fixed with a binding screw to a compartment 325 of the disk tray 303. The optical pickup unit 304 is held between the bottom plate 322 and disk tray 303.
The above base chassis 315 includes an iron-made frame 327. The frame 327 is shaped to have a generally rectangular form. It has formed therein an opening 328 through which the objective lens 312 on the pickup base 317 faces directly the signal recording surface of the optical disk 302. The opening 328 is shaped to have a generally rectangular form in which the pickup moving mechanism 318 to move the pickup base 317, pair of guide shafts 316 and the pickup base 317 supported on the guide shafts 316 are disposed. Also, the opening 328 is extended at one longitudinal end thereof a generally circular cut 329 in which there are disposed the circular disk table 313 on which the optical disc 302 is placed and a spindle motor (not shown) which rotates the disk table 313. It should be noted that the base chassis 315 has fixed thereto a rigid substrate (not shown) having a connector 354 for connection of one end of the FCC 310 for connection of the printed wiring board 309 disposed in the body 301 of the disk drive 300 and the optical pickup unit 304 to each other.
The pickup base 317 to write or read information signals to or from an optical disk placed on the disk table 313 has installed thereon at least a light source (not shown) such as a semiconductor laser, objective lens 312 to focus a light beams emitted from the light source onto the signal recording surface of the optical disk 302, a photodetector (not shown) to detect a return light from the recording surface of the optical disk 302, and a drive system which moves the objective lens 312 toward and away from the optical disk 302 (in the focusing direction) and across the optical disk 302 (in the tracking direction). Also, the pickup base 317 has an insertion hole 317b formed in one longitudinal end portion 317a thereof and through which the guide shaft 316 is passed, and an engagement piece 330 formed at the other end 317c thereof opposite to the end portion 317a and which is engaged on the guide shaft 316.
As shown in FIG. 5, the pickup base 317 includes also an engagement member 332 adjacent to the guide shaft 316 and which engages with a lead screw 331 included in the pickup moving mechanism 318 to move the pickup base 317. The engagement member 332 is projected to under the lead screw 331 from the end portion 317a through which the insertion hole 317b is formed, and has a transmission member 333 which engages with the lead screw 331. The transmission member 333 has provided at an end thereof an engagement projection 334 engaged in threads on the lead screw 331. The transmission member 333 is formed from an elastic material such as a leaf spring, so that the engagement projection 334 is kept always in mesh with the threads on the lead screw 331. Having fixed thereto the transmission member 333 which converts the rotation of the lead screw 331 into a linear movement, the pickup base 317 is moved radially of the optical disk 302 as the lead screw 331 is rotated.
Supported on the pair of guide shafts 316 disposed long the mutually opposed lateral edges of the opening 328 in the base chassis 315, the pickup base 317 is guided by the guide shafts 316 in moving between the inner and outer circumferences of the optical disk and the objective lens 312 is kept exposed to the signal recording surface of the optical disk 302 through the opening 328.
As shown in FIG. 6, the pickup moving mechanism 318 includes the lead screw 331 provided adjacent to the pair of guide shafts 316 an extending radially of the optical disk, and a DC motor 335 connected to a base end 331a of the lead screw 331 to rotate the lead screw 331.
The lead screw 331 is borne at the end 331b thereof in a frame 337 by means of the base end 331a and bearing 336. With the frame 337 fixed with a binding screw or the like to the base chassis 315 of the optical pickup unit 304, the pickup moving mechanism 318 is provided adjacent to one of the guide shafts 316. The lead screw 331 is threaded, and the engagement member 332 of the pickup base 317 is slideably engaged in with the threads on the lead screw 331. Therefore, when the lead screw 331 is rotated by the DC motor 335, it can move the pickup base 317 radially of the optical disk 302.
As mentioned above, the lead screw 331 is rotated by the DC motor 335 and the DC motor 335 will not provide any torque unless it runs at a high speed. Therefore, various points of contact of the pickup moving mechanism 318 will be abraded heavily. In case the DC motor 335 is connected to the lead screw 331 via a gear mechanism to move the pickup base 317, the operating noise will be increased.
On this account, a step motor is used as the DC motor 335 in the present invention and the pickup base 317 is moved radially of the optical disk 302 by supplying the DC motor 335 with a rectangular wave for stepwise run.
The disk tray 303 having the above optical pickup unit 304 housed therein has formed at a main side 340a of a generally rectangular tray body 340 thereof a concavity 341 in which the optical disk 302 is to be received, and at the rear side of the tray body 340 a compartment 325 in which the optical pickup unit 304 is housed. The optical pickup unit 304 housed in the compartment 325 has the cover member 343 fixed thereto. The concavity 341 has formed in the bottom thereof an opening 344 through which the cover member 343 is exposed. Thus, the cover member 343 forms a part of the concavity 341. Also, the disk table 313 supporting the objective lens 312 included in the optical pickup unit 304 and the optical disk 302 to be rotatable is exposed through the opening 344 in the cover member 343.
The concavity 341 of the disk tray 303 is generally circular, and it is defined by first to fourth walls 345 to 348 formed generally circular as shown in FIG. 3.
Of the above walls, the first wall 345 is formed at the side of the rear end 303a of the disk tray 303 to extend over the opening 344 formed in the bottom of the concavity 341. The first wall 345 has a constant clearance C between the lower edge 345a thereof opposite to the concavity 341 and the cover member 343 exposed through the opening 344 in the concavity 341.
Note that the second to fourth walls 346 to 348 are generally circular and rise from the concavity 341.
The disk tray 303 is formed by injection molding of a synthetic resin having a high rigidity such as PEP (polyphenylene ether), for example.
As shown in FIG. 7, a holding mechanism 360 for holding the disk tray 303 inside the device body 301 is formed in the compartment 325 formed the rear side of the disk tray 303 for housing the optical pickup unit 304. The holding mechanism 360 includes a forcing mechanism 361 to force the disk tray 303 to outside the device body 301, and an engagement mechanism 362 which is engaged on an engagement projection 326 provided upright on the lower half 307 of the device body 301 to achieve an engagement between the disk tray 303 and device body 301.
The forcing mechanism 361 includes an ejection member 365 to force the disk tray 303 to outside the device body 301 when pressed to a rear wall 301a of the device body 301, and a coil spring 366 which forces the ejection member 365 toward the rear wall 301a. 
The ejection member 365 is shaped to have a generally stick-like shape and has a flange 365a formed nearly at the longitudinal middle thereof. Also, the ejection member 365 is disposed in a compartment 368 defined in the disk tray 303. The compartment 368 is formed near one side of the disk tray 303 to extend in the direction of inserting or ejecting the disk tray 303. The compartment 368 has a through-hole 368a formed therein at the rear end 303a of the disk tray 303 and a retention step 368b formed nearly in the middle thereof to retain the flange 365a of the ejection member 365. Also, the compartment 368 has a retention wall 369 formed in a position inner than the retention wall 368b and correspondingly near the front end 303b of the disk tray 303 to retain one end of the coil spring 366. The retention wall 369 has formed therein an insertion hole for the ejection member 365 and also an insertion space 370 for reception of the ejection member 365. The insertion hole 370 is formed in a portion inner than the retention wall 369 and further near the front end 303b of the disk tray 303.
The coil spring 366 is disposed between the retention step 368a and retention wall 369 of the compartment 368. It has the ejection member 365 inserted in the hollow space thereof, and is retained at one end thereof on the flange 365a of the ejection member 365 and at the other end on the retention wall 369.
In the forcing mechanism 361 constructed as above, the coil spring 366 forces the flange 365a of the ejection member 365 to the rear end 303a of the disk tray 303, and thus the ejection member 365 is projected from the rear end 303a as shown in FIG. 7. In this condition, the flange 365a of the ejection member 365 is retained on the retention step 368b of the compartment 368.
Next, when the disk tray 303 is housed in the device body 301, the ejection member 365 projecting from the disk tray 303 is butted to the rear wall 301a of the device body 301 and pressed back to the front end 303b of the disk tray 303 against the force of the coil spring 366. Thus, the coil spring 366 is pressed to the flange 365a of the ejection member 365 and compressed to the front end 303b. When the disk tray 303 is engaged on the device body 301 by an engagement mechanism 362 which will be described in detail later, the coil spring 366 will keep a force which forces the ejection member 365 toward the rear end 303a as shown in FIG. 8. It should be noted that at this time, the ejection member 365 is passed through the insertion hole formed in the retention wall 369 into the insertion space 370.
Then, the disk tray 303 and device body 301 are disengaged by the engagement mechanism 362 from each other, the coil spring 366 forces the flange 365a of the ejection member 365 to the rear end 303a. The ejection member 365 will be projected from the rear end 303a of the disk tray 303 through the through-hole 368a, and butted to the rear wall 301a of the device body 301. As the ejection member 365 is further forced, the coil spring 366 extends to the front end 303b of the disk tray 303 from the flange 365a of the ejection member 365 butted to the rear wall 301a of the device body 301. Therefore, as the retention wall 369 is forced to the front end 303b, the coil spring 366 will eject the disk tray 303 to outside the device body 301.
Next, there will be explained the engagement mechanism 362 which engages with the disk tray 5 and device body 7 when the disk tray 5 is inserted into the device body 7.
As shown in FIG. 9, the engagement mechanism 362 includes an engagement projection 326 provided on the lower half 307 of the device body 301 for engagement with the disk tray 303 to retain the disk tray 303 engaged in the device body 301, and an engagement piece 371 provided on the disk tray 303 and pivoted in a direction for engagement on the engagement projection 326.
The engagement projection 326 is provided near one end of the lower half 307 of the device body 301 as will be seen in FIG. 1. The engagement projection 326 is formed to be generally cylindrical. When the disk tray 303 is inserted into the device body 301, the engagement projection 326 will be engaged on the engagement piece 371 formed at the disk tray 303 to hold the latter inside the device body 301.
As shown in FIG. 9, the engagement piece 371 engaged on the engagement projection 326 includes a retaining portion 372 formed like a hook to catch the engagement projection 326, a body 373 having the retaining portion 372 formed at the end thereof, a stud 374 provided at the side of the base end of the body 373 and about which the engagement piece 371 is pivoted, and an abutting portion 376 to be put into contact with an eject button 375 which will be described in detail later. The engagement piece 371 is pivotably about the stud 374 in the direction of arrow D in FIG. 9 or in a direction opposite to the direction of arrow D. A torsion coil spring 377 is wound on the stud 374 to always force the engagement piece 371 for pivoting in the direction of arrow D in FIG. 9. With the engagement piece 371 pivoted in the direction of arrow D in FIG. 9, the retaining portion 372 is positioned on the moving orbit of the engagement projection 326 provided on the device body 301.
Note that the eject button 375 put in contact with the abutting portion 376 is provided on a control panel (not shown) formed at the front end 301b of the device body 301. When the user presses the eject button 375 for drawing out the disk tray 303, it presses the abutting portion 376 to pivot the engagement piece 371 in the direction opposite to the direction of arrow D in FIG. 9.
The engagement piece 371 has a bevel 373a formed thereon to extend from the end of the body 373 in the moving direction of the engagement projection 326 and protrude in the direction of arrow D. The hook-shaped retaining portion 372 is formed at the protruding end of the bevel 373a. Also, the engagement piece 371 has the abutting portion 376 formed at the side thereof opposite to the side where the bevel 373a is formed. Namely, the stud 374 is located between the abutting portion 376 and bevel 373a. Therefore, when the abutting portion 376 is pressed by the eject button 375, the engagement piece 371 is pivoted in the direction opposite to the direction of arrow D in FIG. 9. As the retaining portion 372 is thus pivoted in the direction of arrow D, it catches the engagement projection 326 and holds the disk tray 303 inside the device body 301. When the retaining portion 372 is pivoted in the direction opposite to the direction of arrow D to release the engagement projection 326, thus allowing the disk tray 303 to be ejected from inside the device body 301 by the aforementioned coil spring 366 and ejection member 365.
More specifically, as the disk tray 303 is inserted into the device body 301, the engagement projection 326 provided on the lower half of the device body 301 moves in the direction of arrow H in FIG. 9, abuts the bevel 373a, and thus pivots the engagement piece 371 in a direction opposite to the direction of arrow D. When the engagement projection 326 has moved over the end of the bevel 373a, the engagement piece 371 is pivoted in the direction of arrow D under the force of the torsion coil spring 377 and the retaining portion 372 is positioned again on the moving orbit of the engagement projection 326. Thus, the engagement piece 371 has the retaining portion 372 thereof engaged on the engagement projection 326 and the disk tray 303 engages with the device body 301.
For ejection of the disk tray 303 to outside the device body 301, the user operates the eject button 375 which will press the abutting portion 376. When the abutting portion 376 is pressed by the eject button 375, the engagement piece 371 is pivoted in the direction opposite to the direction of arrow D in FIG. 9. When the engagement piece 371 is thus pivoted in the direction of arrow D, the retaining portion 372 is retracted from the moving orbit of the engagement projection 326 and thus released from the engagement projection 326. Thus, the disk tray 303 and device body 301 are disengaged from each other, and the disk tray 303 is forced out of the device body 301 by the aforementioned forcing mechanism 361.
The disk tray 303 constructed as above has also an engagement portion 349 formed on each of the opposite lateral sides of the tray body 340 and which engages with the guide member 308 formed on the lower half 307. Since the engagement portion 349 is slideably engaged on the guide member 308, the disk tray 303 is guided in moving into, or to outside, the device body 301, and thus carried along with the optical pickup unit 304 into, or to outside, the device body 301.
As shown in FIG. 10, the FCC (flexible printed circuit) 310 connecting the optical pickup unit 304 housed in the disk tray 303 and the printed wiring board 309 provided on the lower half 307 of the device body 301 to each other is shaped to have a generally U-shaped form, and includes first and second linear arm portion portions 350 and 351 adjacent to each other and extending in parallel, and a circular portion 352 joining the first and second arm portion portions 350 and 351 to each other.
The first arm portion 350 is directed at the end thereof toward the rear end 307d of the lower half 307 and connected to a connector (not shown) provided at the bottom of the printed wiring board 309. Also, the first arm portion 350 is fixed to the bottom of the lower half 307. The second arm portion 351 contiguously joined to the first arm portion 350 via the circular portion 352 has the end portion 351a folded back toward the front end 307a of the lower half 307 and connected to the connector 354 provided on the optical pickup unit 304 housed in the disk tray 303. The second arm portion 351 is not fixed to the device body 301 and disk tray 303, but as the disk tray 303 is moved, the second arm portion 351 is moved into, or to outside, the device body 301 with the circular portion 352 being taken as a reference position.
More particularly, as the disk tray 303 is moved into, or to outside, the device body 301, the FCC 310 has also the second arm portion 351 thereof moved into the device body 301 as shown in FIGS. 11A to 11C. At this time, the second arm portion 351 is folded back toward the front end 307a of the lower half 307, resulting in a bending 355. As the disk tray 303 is moved, the bending 355 shifts in the moving direction of the disk tray 303. Namely, when the disk tray 303 is ejected to outside the device body 301, the second arm portion 351 of the FPC 310 is also folded back in a position near the circular portion 352 and has the end portion 351a thereof ejected to outside the device body 301 as shown in FIG. 11A. Thus, the bending 355 is formed in a position near the circular portion 352. Then, as the disk tray 303 is moved into the device body 301, the bending 355 of the second arm portion 351 of the FPC 310 shifts toward the end portion 351a correspondingly as shown in FIG. 11B. When the disk tray 303 is fully housed in the device body 301, the bending 355 of the second arm portion 351 of the FPC 310 is formed in a position near the connection with the connector 354 provided on the optical pickup unit 304 as shown in FIG. 11C.
For accurate writing or reading data to or from an optical disk used in the CD-R/RWs or DVD-ROM, a light beam emitted from the optical pickup should be incident perpendicularly upon the signal recording surface of the optical disk. For such an optical disk drive, the relevant Standard permits a fixed range of the angle formed between the signal recording surface of the optical disk and the optical axis of the objective lens which focuses the light beam onto the optical disk.
Also, in such an optical disk drive, in case a light beam is not incident perpendicularly upon the signal recording surface of the optical disk, the angle of the light beam in relation to the signal recording surface is detected, and the relation in angle between the objective lens which focuses the light beam and the signal recording surface of the optical disk is adjusted by a skew adjusting mechanism.
As shown in FIG. 4, the skew adjusting mechanism 400 is provided inside the base chassis 315 in which the pickup base 317 is provided. It is provided at each of the opposite ends of each of the guide rails 316 in pair which guide the pickup base 317 in moving radially of the optical disk 302. As shown in FIG. 12, the skew mechanism 400 includes a spring 402 disposed in a holder 401 fitted on one end of the guide rail 316 and which supports the upper portion of the guide rail 316, and an adjusting screw 403 provided to abut the lower side of the guide rail 316 and which presses the guide rail 316 vertically to adjust the height of the guide rail 316.
The above holder 401 is installed to a rear side 405a of a main plate 405 included in the base chassis 315, and has formed therein an insertion opening 406 in which the end portion of the guide rail 316 is inserted. The holder 401 has the end portion of the guide rail 316 inserted therein through the insertion opening 406, and the spring 402 provided therein as shown in FIG. 12. The holder 401 has also formed in the bottom of the insertion opening 406 a screw hole 407 in which there is inserted an adjusting screw 403.
The spring 402 is a cylindrical coil spring and forces the guide rail 316 downward. The adjusting screw 403 is inserted in the screw hole 407 formed in the bottom of the holder 401 and abuts, at the top thereof, the lower side of the guide rail 316.
The above skew adjusting mechanism 400 adjusts the height of the guide rail 316 by adjusting the length, projected into the holder 401, of the adjusting screw 403. Thus, the relation in angle between the objective lens 312 which focuses the light beam and the signal recording surface of the optical disk 302 can be adjusted so that the light beam can be incident perpendicularly upon the signal recording surface.
However, the thickness of the skew adjusting mechanism 400 is a problem in implementing a demanded thinner and more compact design of the optical disk drive. That is, in case the thickness of the VD-ROM drive casing, for example, is adapted to that of a hard disk drive having a thickness of 9.5 mm in order to reduce the thickness of the disk drive itself, no other than the adjusting margin for the height of the guide rail 316 can be reduced since the parts of the disk drive are fixed in height. Therefore, it is almost difficult to reduce the thickness of the disk drive.
Note here that the DC motor 335 included in the pickup moving mechanism 318 includes a generally rectangular housing 338 which covers the base chassis 315 as a whole including the width, as shown in FIG. 6A. Therefore, the housing 338 has a width (6 mm, for example) equivalent to the thickness of the base chassis 315 as shown in FIG. 6B.
Also, the thickness of the pickup moving mechanism 318 is a problem in implementing the above demanded thinner and more compact design of the optical disk drive. Namely, in case the thickness of the VDV-ROM drive casing, for example, is adapted to that of the hard disk drive having a thickness of 9.5 mm in order to reduce the thickness of the disk drive itself, covering the entire housing 338 of the DC motor 335 with a metallic plate will make it difficult to reduce the thickness of the disk drive to 9.5 mm since the parts of the disk drive are fixed in height.
Note that in the aforementioned optical pickup unit 304, the transmission member 333 is formed from an elastic material such as a leaf spring or the like and the engagement projection 334 is forced by the leaf spring to always be in mesh with the threads on the lead screw 331. Therefore, to move the pickup base 317 stepwise to a desired position by the DC motor 335 supplied with a predetermined rectangular-wave pulse, the engagement projection 334 has to be movable without being disengaged from the threads on the lead screw 331. On this account, the transmission member 333 should has the engagement projection 334 thereof engaged in the threads on the lead screw 331 under a strong force.
Since the DC motor 335 as a step motor provides only a weak torque, however, if the transmission member 333 is engaged in the threads on the lead screw 331 under an excessively strong force, the lead screw 331 cannot be rotated and thus the pickup base 317 cannot be moved quickly.
On the other hand, if the force for application to the transmission member 333 is weakened, the engagement projection 334 will be disengaged from the threads on the lead screw 331, supply of the rectangular-wave pulses for a predetermined number of steps to the DC motor 335 cannot move the pickup base 317 to a predetermined position and thus positioning of the pickup base 317 is inconveniently impossible.
Note here that in the disk drive 300, since the disk tray 303 formed from PEP, optical pickup unit 304 formed from iron and cover member 343 formed from aluminum are joined to each other, their differences in coefficient of linear thermal expansion from one another will cause each of the components to be distorted as the component has a higher temperature. That is, as mentioned above, the disk tray 303 is formed from a rigid material such as PEP (polyphenylene ether), the base chassis 315 of the optical pickup unit 304 housed in the disk tray 303 is formed from iron (Fe), and the cover member 343 installed to the top of the base chassis 315 and exposed through the opening 344 in the disk tray 303 is formed from aluminum (Al). Namely, these disk tray 303, base chassis 315 and cover member 343 are different in linear expansion coefficient from each other. More specifically, the linear expansion coefficient of PPP is 2.8×10−5/mm° C., while the linear expansion coefficient of aluminum is 2.4×10−5/mm° C. and that of iron is 1.2×10−5/mm° C.
Each of the disk tray 303, base chassis 315 and cover member 343 is distorted due to such differences in linear expansion coefficient, namely, due to differences in thermal shrinkage, as they are elevated in temperature when the disk drive 300 is driven. More particularly, the aluminum-made cover member 343 is warped from the lateral edge of the opening 344 toward the optical disk 302 and will have a sliding contact with the signal recording surface of the optical disk 302 received in the concavity 341 in some cases. Particularly, since there is defined a clearance C between the lower edge of the first wall 345 and the cover member 343 (see FIG. 3), the cover member 343 will be bent toward the clearance C. Also, since the first wall 345 is located along the outer circumference of the optical disk 302 and thus incurs a relatively large axial runout, it is likely to have a sliding contact with the cover member 343.
Note here that in the aforementioned disk drive 300, the holding mechanism 360 for holding the disk tray 303 inside the device body 301 is provided to disengage the engagement mechanism 362 from the engagement projection 365 by means of the eject button 375. If the eject button 375 is pushed by mistake while data is being written to or read from the optical disk 302, the disk tray 303 and device body 301 are disengaged from each other, possibly causing a trouble in the data write or read.
Also note here that in order to prevent the FPC 310 from being caught between the device body 301 and the rear side 302a of the disk tray 303 while the disk tray 303 is being housed into the device body 301, the FPC 310 is formed to have the first arm portion 351 changed in rigidity in places.
That is to say, when the disk tray 303 is outside the device body 301, a clearance 356 is defined between the disk tray 303 and device body 301 as shown in FIG. 11A. Therefore, if the end portion 351a of the flexible FPC 310 is bent to below the clearance 356 when the disk tray 303 is housed into the device body 301, the FPC 310 will be caught between the disk tray 303 and device body 301 as shown in FIG. 13.
On this account, the FPC 310 has a cover lay 357 attached on the end portion 351a of the second arm portion 351. The cover lay 357 increases the rigidity of the end portion 351a of the second arm portion 351 in comparison with that of the rear end portion 351b. Therefore, the FPC 310 is prevented from being bent at the higher-rigidity end portion 351a thereof to below the clearance 356 when the disk tray 303 once ejected to outside the device body 301 is housed again into the device body 301, while the lower-rigidity, flexible rear end portion 351b of the second arm portion 351 is bent, so that the disk tray 303 is positively moved into the device body 301.
However, when the disk tray 303 is fully housed in the device body 301, the FPC 310 having the cover lay 357 attached on the end portion of the second arm portion 351 will have the bending 355 of the second arm portion 351 thereof shifted toward the end portion 351a and thus the bending 355 be formed in a position near the connection with the connector 354 provided on the optical pickup unit 304 as shown in FIG. 11C. The nearer to the connection with the connector 354, the larger the load to the bending 355 becomes. For a longer distance between the connection with the connector 354 and the bending 355, however, the FPC 310 should have an extra length, which will add to the cost of manufacture. Also, the cover lay 357 attached on the end portion 351a of the second arm portion 351 increases the rigidity and thus the load to the end portion 351a as well. Further, since the thickness of the device body 301 of the disk drive 300 is minimized to meet the requirement for the thinner design of a host device in which the disk drive 300 is to be used, the curvature of the bending 355 will be larger as the device body 301 is designed thinner and thus the load to the bending 355 be larger.
As the disk tray 303 is repeatedly inserted and ejected with a large load being applied to the second arm portion 351 of the FPC 310 at each time, the end portion 351a of the second arm portion 351 will crack and the circuit pattern formed in the FPC 310 will be broken.